a couple things from this thread. first people that are smoking for the first time usually get shit weed, so it doesnt get them high because they don't inhale enough THC. another problem, they dont inhale.
second, if weed was legalized im pretty sure it would be illegal to grow personally, just like tobacco.
and third, there is no "weed receptor" in your brain. there are proteins that make endocannabinoids (a natural THC like substance in every living thing with a brain), that in turn attach to receptors in the brain that control emotions and things similar to what weed does when your high. so the THC attaches to a receptor for pain, and tells your brain there is less pain, or more hunger, and so on. it is very possible to get high your first time, but your brain either doesnt recognize these foreign cannabinoids and rejects them, or it fights back with other receptor altering substances. or you dont know what being high feels like. the difference between levels of THC and cannabinoids in weed also changes what effects you get too.